Sear and trigger mechanism



Nov. 24, 1964 D. F. ANDERSON ETAL 3,158,063

SEAR AND TRIGGER MECHANISM Filed June 3, 1957 9 Sheets-Sheet 1 FORWARD Q LEFT LOADER i Mi FIG. I

INVENTORS DAVID F. ANDERSON RQBERT BUTTERWORTH RICHARD E. TAYLOR BY fld Q/Ew ATTORNEYS Nov. 24, 1964 Filed June 3, 1957 D. F. ANDERSON ETAL v SEAR AND TRIGGER MECHANISM 9 Sheets-Sheet 2.

llllllllllllllllllllllHlllllllllllllllllllilllllllllllllllllll|lilllllIllIlllllllllllllllllllllllllllllllllllllilIHIIHIIIIII FIG.24

INVENTOR-S' DAVID F. ANDERSON ROBERT BUTTERWORTH IGHARD E. TAYLOR Y 16% Ql wm ATTORNEYS Nov. 24, 1964 D. F. ANDERSON ETAL 3,153,063

SEAR AND TRIGGER MECHANISM Filed June 3, 1957 9 Sheets-Sheet 3 FORWARD Q q IIIIIIIIHIHHllllllllllllllHllllllIll|IIIIIHIIIHlllllllllllllilllllIllllllllllllllllllllllllllllllll ||||l|| INVENTORS DAVID F. ANDERSON ROBERT BUTTERWORTH RICHARD E. TAYLOR 21mm 69 g m FIG.3

Nov. 24, 1964 D. F. ANDERSON ETAL 3,158,063

SEAR AND TRIGGER MECHANISM Filed June 3, 195'? 9 Sheets-Sheet 4 IIIHHIIIIIIIIIIHIIIH!llllllllIIIIIIHHIIIIIUI|| IHHII FIG. 4

INVENTORS DAVID F. ANDERSON ROBERT BUTTERWORTH RIGHARD E. TAYLOR ATTORNEYS Nov. 24, 1964 D. F. ANDERSON ETAL 3,158,063

SEAR AND TRIGGER MECHANISM Filed June 5, 1957 9 Sheets-Sheet 5 INVENTORS DAVID F. ANDERSON ROBERT BUTTERWORTH BY TAYDLOR FIG.5

W. ATTORNEY Nov. 24, 1964 D. F. ANDERSON ETAL 3,158,063

, SEAR AND TRIGGER MECHANISM 9 Sheets-Sheet 6 Filed June 5, 195'? BACKPLATLE .mlIIIIIIIIIIIIIIIIIIIIlllllllllllli If I 4 Tmaean MECHAMSM 794 747 744 G34 G45 sen MECHANISM m4 FIG. 6

\ GSI 6 @FoRwA m GUN MECHAMSM I07 SPRocKET 6H GUN RECEIVE 625 SUDE 64-4 INVENTORS' DAVID F. ANDERSON ROBERT BUTTERWORTH RICHARD E. TAYLOR I BY SUDE 644- M ATTORNEYS Nov. 24, 1964 D. F. ANDERSON ETAL 3,158,063

SEAR AND TRIGGER MECHANISM Filed June 5, 195'? 9 Sheets-Sheet 7 F|G 9 an ace am e07 TION 639 FIG. IO ROUND POSI M %k\ SOS- I E G45 G4G\ SLIDE 644 54 0 INVENTORS DAVID F. ANDERSON ROBERT BUTTERWORTH RICHARD E. TAYLOR ATTORNEYS SEAR AND TRIGGER MECHANISM Filed June 3, 1957 9 Sheets-Sheet 8 FIG. u

FIG. I2

795 4 615 796 806 637* I BIG l I 717 769 765 807 Ai J 1 u 776 ,2 762 L L 4'14 V W H 793 4 E6 79! 759 III III I 0 7 WA 1 77 768 7 FORWARD TENSION BY SPRINGSGBS 644- INVENTORJ DAVID F. ANDERSON ROBERT BUTTERWORTH RICHARD E. TAYLOR m ATTORNEYS Nov. 24, 1964 D. F. ANDERSON ETAL 3,158,063

SEAR AND TRIGGER MECHANISM 9 Sheets-Sheet 9 Filed June 5, 1957 INVENTORS DAVID F. ANDERSON ROBERT BUTTERWORTH RICHARD E. .TAYLOR BY Q/3 W ATTORNEYS United States Patent 3,i58,ll63 SEAR AND TREGGER ME CiiANiSll/l Bavid F. Anderson, McLean, Va, and Robert Butter- Worth, District Heights, and Richard E. Taylor, Hyattsville, Md, assignors to the United States of America as represented by the Secretary of the Navy Filed June 3, 1%7, Ser. No. @3518 4- tllaims. (6i. 89-4137) (Granted under Title 35, U5. (lode (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This application discloses and claims a portion of a complete system disclosed and claimed in copending application Serial No. 663,319, filed June 3, 1957, now Patent No. 2,877,266, for Rapid Fire Gun System.

The present invention relates to a sear and trigger mechanism capable of functioning in association with a rapid fire gun and mount therefor. More particularly, this invention is directed to a sear and trigger mechanism for use with a Weapon suitable for a saturation zone type of protective or assault fire and which is especially well adapted for shipboard antiaircraft use.

Heretofore, antiaircraft guns of both large and small calibers have been devised for employment against high and low altitude attacking planes. Although, the large caliber guns are effective at high altitudes when properly used, these guns are generally inefiective at low altitudes and short ranges because, among other reasons, of their slow rate of fire and the more effective evasive action taken by aircraft at low altitudes. Consequently, guns generally in use against low flying aircraft have been of a small caliber and in the machine gun class in order to obtain a rapid rate of fire and cope with the evasive action of aircraft attempting to avoid the zone of fire. However, the use of armor around the vital parts of aircraft has increased considerably and it has been found that the smaller caliber guns could make a number of hits without reaching a vital part, and, therefore, the attacking aircraft would, in many cases, continue the attack.

With conventional guns, as the caliber increases, the wei ht of the many gun components as well as the gun itself increases greatly. Heavier structural members are needed to load and transfer ammunition. The recoil forces generated require heavier mounting and driving structures. Consequently, aboardship the number of guns that can be installed is limited by the weight factor alone. Furthermore, the handling of conventional large caliber case ammunition presents problems because of its size and Weight, such ammunition not being adapted to belt or clip type feeding as used in the machine gun class weapons.

The use of large guns and mounts generally prohibits the stowage of ammunition or maintenance of magazines on the same level on which the gun is mounted because of space requirements. Thus, the ammunition stowage is at a lower level, often employing three or more decks of the ship to contain all the necessary equipment. Location below decks complicates the problem of feeding ammunition to large caliber guns and necessitates the in stallation of elaborate ammunition hoists with associated large gains in overall weight and complexity of the ammunition handling equipment.

The present invention overcomes many of the disadvantages of the prior art weapons-in that it provides an automatic, rapid fire sear and trigger mechanism for oporation during the firing of symmetrically cased rocket assisted projectiles of relatively large caliber. The entire mechanism is relatively small and compact as compared with prior art mechanisms employed for similar caliber weapons which are not capable of handling in any given time interval an equivalent amount of ammunition as handled by the present invention.

The projectile isenclosed in a symmetrical container or case which functions both as a storage case and as an expendable gun chamber when the projectile is fired. The projectile is fired by the ignition of a reduced powder charge within the container and is propelled through the barrel at a relatively low velocity. While within the rifled gun barrel, the rocket propellent motor is ignited by the hot gases of the reduced powder charge and thereafter the projectile accelerates to a much higher velocity comparable to conventional projectiles during flight. Sufiicient spin is imparted by the rifled tube of the launcher and the canted nozzle of the spin-stabilized rocket to make the rocket stable as it emerges from the tube. The canted nozzles of the rocket motor provide additional spin during flight. The conventional recoil is substantially reduced because of the low firing pressures produced in the system with which the present invention is employed. Machine gun rates-of-fire are obtained by the use of expendable gun chambers made feasible by the low powder pressure created when each round is fired. The employment of the expendable gun chambers makes possible the moving of the rocket assisted ammunition laterally into axial alignment with the gun barrel without the necessity of axial ramming and extracting operations as is common with conventional cased ammunition.

It is, therefore, an object of the present invention to provide a sear and trigger mechanism capable of performing at a high cyclic rate in a Weapon for firing large caliber rocket assisted projectiles.

A further object resides inthe provision of a rapid fire rocket launching system having an operating slide lockingmeans operable when the gun is charged and also when any unsafe firing condition exists.

Another object of the present invention resides in the provision of a rapid fire rocket launching system including a sear and trigger means operated by round contact for locking and unlocking an operating slide in accordance with predetermined gun operating conditions, the operating slide actuating associated devices for controlling the entry and exit of rounds to and from the firing position, respectively.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a top plan view with portions broken away of a twin gun mount embodying the present invention;

FIG. 2 is a vertical sectional view of the mount of FIG. 1 taken along a line substantially corresponding to line 2-2 of FIG. 1;

FIG. 3 is a vertical sectional view of the gun mount of FIG. 1 taken along a line substantially corresponding to line 33 of FIG. 1;

FIG. 4 is a front elevational view of the gun mount of FIGS. 1, 2 and 3 with a portion of the shield broken away to better illustrate the relative locations of certain mechanisms of the system;

' FIG. 5 is a rear elevational view of the gun mount with portions of the shield and stand removed;

FIG. 6 is a rear perspective view of the gun mechanism with the top cover raised, and the backplate opened and the feed drive slide removed;

FIG. 7 is a top perspective view of the feed drive slide removed from the gun mechanism of FIG. 6;

FIG. 8 is a bottom perspective view of the feed drive slide of FIG. 7;

PEG. 9 is a top plan View of the sear trigger mecha- 3 nism mounted on the rear feed sprocket bearing support of the" gun receiver, the bearing support having been removed from the gun mechanism;

FIG. is a rear elevational view of the sear trigger' mechanism with its associated scar and feed operating slide shown positioned therebeneath;

FIG. 11 is a front elevationalview of the sear trigger mechanism;

FIG. 12 is a slightly enlarged vertical sectional view taken through the sear, Operating slide, and a portion of the backplate, the slide being shown in its rearward seared position; and

FIG. 13 is an exploded perspective schematic view of the scar and seartrigger mechanism elements.

General Mount Description Referring first to FIGS. 1 through 5 which are general arrangement views of the entire system in which the present invention is employed, it will be observed that a twin weapon mount, generally designated by numeral 100, is shown mounted on a fixed stand 101 such as those which are presently in use on naval vessels. The, mount comprises a platform carriage 102 which supports thereabove gun and round handling mechanisms and carries therebeneath mount drive and power components. The carriage 102 is rotatably supported for movement in train on roller bearings (not shown) which engage a mating roller path (not shown) formed in a fixed training circle gear 103. A carriage mounted drive pinion 104 is drivingly meshed with the training circle 103 for driving the mount in train. Additional power and associated equipment such as motors, firing cutouts, brakes, clutches and buffers, are also carried beneath the carriage.

Located centrally atop the carriage is a pair of trunnion bearings 105 which support therebetween, an elevatable cradle 106. An elevating arc 130 is secured to the left hand side of cradle 106, as viewed in FIG. 5, and is driven by a conventional elevating pinion (not shown) to move the entire cradle in elevation. An elevation stop buffer 131 and a depression stop buffer 132 are provided, as shown in FIGS. 2 and 4. The central portion of the cradle supports a pair of right and left hand gun mechanisms 107 and 108 each gun mechanism having a rifled barrel 1G9 and 110, both respectively, protruding from the front portion of the cradle. A twin case ejection system 111 is also carried by the cradle and is located between the gun mechanisms. Secured to opposite sides of the cradle and elevatable therewith, are right and left hand, round transfer mechanisms 112 and 113, respectively, the outer ends of which are supported in bearings 114 carried by similar right and left hand pedestals 115 secured to the top of the carriage 102. An elevation response are 116 is also secured to the outboard ends of each round transfer mechanism and is in contact with elevation response gearing 117 connected to suitable firing cutouts during adjustment of gun elevation. In addition, the elevation response gearing repositions certain elements in the transfer mechanism drive gearing to maintain alignment of feed starwhe'els at the round entry end of the transfer mechanismregardless of angle of gun elevation. This is accomplished by means of suitable differential gearing (not shown). Right and left hand round storage magazines 118 and 119, respectively, are mounted outboard of the cradle on the carriage and overlie the major portion of the top surfaces of each round transfer mechanism. Right and left magazine loaders 120 and 121, respectively, are mounted on the forward and lower front end of each magazine through which rounds may be fed to the magazine to load endless round carrying chains moving through each magazine. Access doors 122 permit access to the loader during periods of magazine loading and unloading.

A shield 123 secured to the carriage, completely encloses the mount units and forms a Weather seal for the mount units and mount operator. The top central portion of the shield supports a control compartment 124 which includes a transparent observation dome 125 extending above the shield. A gun port shield 126 mates with a circular path 127 formed in the shield and may have inflatable waterproof sealing elements (not shown) for sealing the movable elements when in stowed condition.

A fixed case ejection chute 128, formed in the central floor portion of the carriage, is curved to conform with the sweeps of a pair of case deflector assemblies 129 carried by the aforementioned case ejection system 111 and delivers empty cases out of the front end of the mount. to carry water to and from the gun cooling system.

Gun Mechanism Referring now to FIG. 6 the gun mechanism receiver 625 has a forward tubular barrel receiving portion 626, a flattened rear floor portion 627, a pivotable top cover 612 overlying the floor portion and forming a support for round engaging pawls 593. Thus pawls 593 and the floor 627 define a round entry door, generally designated at 628. A rear, readily removable back plate 629 joins the floor and the cover.

The flattened rear floor portion 627 lies between a pair of inner and outer integrally cast, longitudinally extending side rails 633 which are raised from the main floor portion 634 and support forward and rearward drive sprocket bearing supports 635 and 636, respectively.

Each of the bearing supports 635 and 636 is bolted at its base to the rails 633 of the receiver 625, and the top of each support is flattened to form forward and rearward lower round entry guide rails 637. Looking forward in FIG. 10, the rails have a reversed S-shaped con figuration, the round entry rail ends 638 being on the same plane with the rounds feeding into the gun mechanism from the transfer mechanism 112. The round exit rail ends 639 are raised to a height so as to place the moving round in axial alignment with gun barrel 109 and an adjacent ejection mechanism 111.

As shown in FIG. 6, located centrally and above the receiver main floor 634, a feed sprocket assembly 611 is rotatably mounted in and between the forward and rearward bearing supports 635 and 636, respectively. The feed sprocket assembly 611 comprises identical shaftmounted forward and rearward, relatively thin, crossshaped feed star wheels 641, and a thicker, centrally fixed drive star wheel 642 having four identical lobes, each lobe mounting a drive roller 643 at its outer end.

Now referring to FIGS. 7, 8, and 10, located below the sprocket assembly 611 and in engagement with a pair of the drive rollers 643 is a feed sprocket operating slide 644, movable forwardly and rearwardly in slide guides 645 formed in the inner and outer side rails 633 of the floor portion of the receiver.

The upper surface of the slide 644 is generally concave to provide clearance for the feed star wheels 641 during the radial sweeps of the star wheels as forward and rearward motion of the slide is effected. Laterally extended lugs 646 are formed on the left and right sides of the slide and move in the slide guides 645, afore-mentioned.

A suitable switch (not shown) may be operatively connected in the firing circuit in the manner disclosed in application Serial No. 663,319, afore-mentioned, to permit firing only when the slide 644 is in the full forward position. As viewed looking forwardly (FIG. 7), relatively straight left and right drive roller grooves 647 and 648, respectively, are provided on each upper and outer side of the slide in which two of the drive rollers 643 are engaged when the slide is in battery or counter battery. A central, elongated S-shaped, drive roller cam groove 649 communicates with the forward portion of the left roller groove 647 and the rearward portion of the right Suitable coolant lines 133 are employed roller groove 648. This cam groove provides the means for converting straight line motion of slide 64-4 to rotary motion of feed sprocket 611. As the slide moves rear wardly in recoil, a drive roller 643 in the right groove 648 drops into a recessed portion 651 in the forward portion of that groove so that on forward motion of the slide, the right drive roller will then be displaced sideways thereby leading the left drive roller into the curved path of the cam groove 649, thus rotating the feed sprocket in a counterclockwise direction. At the moment the left roller 643 begins to move laterally in the cam groove 649, the right roller in the right groove 643 leaves the latter groove by way of a cutout portion 652 which is laterally opposite the recessed portion 651. Sprocket rotation is decelerated during the final degrees of rotation of its 90 degree movement by means of a spring loaded, stepped cam (not shown) situated adjacent the rear feed star Wheel 641.

Rear Slide Bufler and Searing Means A general description of this portion of the gun mechanism will be helpful before proceeding to the detailed description thereof. In the normal cycle of firing, the operating slide is gas driven rearwardly, is buffered at its rearmost point of travel and is then moved forwardly by spring tension where it is buffered on its forward stroke and the cycle repeated. The scar may operate for a short time at the beginning and end of each burst to hold the slide back and prevent damage to the parts, if for any reason the ammunition rate of feed is too slow. In addition, the operating slide remains locked slightly forward of its rearmost position during the occurrence of one of the following operations:

(1) Charging.-When it is desired to fire the gun, after loaded rounds have been moved to a position adjacent the gun mechanism, the operating slide is moved rearwardly and is latched by a sear mechanism carried by the backplate. Only when rounds have been advanced by the transfer mechanism into a triggering position in the gun will the sear be released.

(2) By-pass operation-In the event the rounds are by-passed, as disclosed in application Serial No. 663,319, aforementioned, prior to reaching the trigger position, the slide will remain latched in the rearmost position assuming that a round has just been fired and the slide moved rearwardly.

(3) Hangfire and misfira-When a hang fire occurs, the delay in firing will cause rounds to be by-passed. In this event, the triggering round will be in position to release the sear and as the hang fired round finally fires, the slide is driven rearwardly and latched. Should the round misfire, the cycle will be the same as in charging, mentioned previously.

Referring now to FlGS. 6, 7, 8, l0, and 12, the backplate 629 functions as part of the gun mechanism and also serves to lock the rear floor portion 627 of the receiver 625 to the rear upper and lower gun receiving portions 743 and 744, respectively, of the cradle assembly. The backplate is pivotally secured at each of its lower sides to the floor of the receiver by means of vertical pins 745 passing through bifurcated horizontally extending hinge ears 746 on the backplate. inge ears 746 receive cooperating extending single ears 747 integral with the rear floor of the receiver. The upper end of the backplate is formed with a pair of vertically extending ears 748 that are received by depending ears 749 formed on the upper part of the cradle and is secured by a pin 751 extending transversely therethrough. Top cover receiving and gripping slots 752 are formed on the sides of the backplate near the upper end thereof to align with suitable rear cover extensions 753 and secure the cover 612 at its rearmost end against lateral and vertical displacement. A firing pin 679, centrally located in the backplate is axially aligned with the gun barrel and used to 6 electrically fire the primer in the closed end of the round container.

Referring particularly to FIG. 6, a slide buffer 754 is provided at the lower rear face of the backplate and comprises a hollow, cylindrical U-shaped spring support 755 stacked series of dished spring washers 756 centrally bored to receive a scar supporting shaft 757 (FIG. 12) which passes therethrough. The front face of the backplate is transversely slotted at 758 to receive an outwardly displaced forward slide buifer plate 759.. Plate 759 is centrally bored to receive and support the forward end of the sear supporting shaft 757. The ends of the plate 759 support a pair of shouldered bolts 761 which pass through openings formed in the backplate on each side of the sear supporting shaft 757, the ends of the bolts contacling a spring engaging rear buffer plate, not shown, to transmit the rearward shock of the operating slide striking the plate 7 59 to the springs 7 56.

Referring particularly to FIGS. 10, 12 and 13 a sear mechanism 764, carried by a sear mounting block 765 is integrally formed with the forward end of the sear supporting shaft 757, the rear end of shaft 757 being threaded to receive a shaft supporting and adjusting nut rotatably carried by the rear wall of the spring support 755, this being fully disclosed in the afore-mentioned application Ser. No. 563,319. Deflection of the sear mounting block 755 is minimized by constant contact of the upper surface of the block with a lower surface 76% of the rear sprocket support 636 and intermittent contact of a pair of outwardly extending shoulders 771 (FIG. 10) formed on the sear mounting block which mate with recesses 772 formed in the slide 644.

In the operation of the sear mechanism 764, (FIG. 12)

' a sea: actuating cam 789 on the slide passes by the sear mecianism to its full rearward position, the slide being buffered and then moved forwardly to a position in which the slide is fully seared or latched. This is accomplished by means of a sear locking pawl 773 pivotally mounted at 774- between a pair of forwardly extending ears 775 formed in the sear mounting block or housing 765. The locking pawl is urged forwardly and is normally held disengaged from the slide by' means of a block mounted spring plunger 776 bearing against a rear vertical extension 777 of the locking pawl. A latch portion 778 of the locking pawl 773 limits clockwise rotation of the pawl by striking an upper wall of recess 779 in the mounting block 765. The scar locking pawl 773 carries a sear pawl actuating cam 7%1 pivotally mounted on the forward end of scar locking pawl 773 as at 782 between a pair of ears 783.

The sear actuating cam 781 is Y-shaped and has a forwardly extending trigger finger engaging arm 784, an upwardly and rearwardly extending pawl engaging arm 785 and a vertically depending slide striker arm 7 86. The cam 781 is urged in a counterclockwise direction (FIG. 12) by means of an angularly and downwardly disposed spring plunger 787 mounted in the locking pawl and bearing against the striker arm 786. Rotation of earn 781 is normally limited by the pawl engaging arm 785 bearing against the front inner face of the sear locking pawl 773 at a point above the pivot 774.

During the searing or latching operation, as the slide moves rearwardly, the forward face of the striker arm 736 is struck by an abrupt inclined surface 7% on an upwardly projecting cam portion 739 formed in the rear floor por tion of the side. This striking of the arm 7% by the surface 788 causes cam 78.7. to rotate clockwise against the compression of spring plunger 787 to retract the striker arm until the slide has moved far enough rearwardly so that the striker arm may drop into a groove 7%. Forward motion of the slide after bufiering will now cause the downwardly extending tip portion of the striker arm 786 to contact a rearwardly inclined wall 792 of groove 791 and thus lift the cam 7 S1 to rotate the sear locking pawl 773 counterclockwise. Sufiicient force is generated to cause the slide engaging latch 778 to fully engage a pair of stop projections 793 formed at the rear portion of the slide, each of the projections 793 having a forward, vertically' inclined latching surface. This inclined latching surface provides means whereby the sear locking pawl 773 may be cammed out of engagement with stop projections 793. Such an arrangement of engagement surfaces materially facilitates the separation of the pawl 773 from the slide which is urged forward by a large force exerted by springs (not shown). The sear mechanism 764 has now fully locked or seared the slide, and in this position the tip portion of the striker arm 786 engages the horizontal portion of cam 789 at a point slightly forward of a vertical line through the pivot point 782 to thereby provide an overcenter toggle action for tl e searing means. 7

Sear Triggering Mechanism As previously stated, the triggering mechanism for sear release is directly controlled by the presence and location of a round entering the gun mechanism; thus as the round is fed into position M'(FIG. by the transfer mechanism, the round contacts and moves the first element of a sear triggering or slide unlatching mechanism 794 mounted on the rearward bearing support 636 of the feed sprocket 611, as best illustrated in FIGS. 9 through 13.

Continuing with a consideration of FIGS. 9 through 13, a round actuated pawl 795 is pivotally mounted at 796 on the rear face of the vertical wall portion of bearing support 636 and has a forwardly and upwardly extending finger 797 projecting through an aperture 798 in the rail 638 and into contact with the medial reduced diameter of the round. Lateral and upward motion of the round causes the finger 797 to move counterclockwise thereby rotating pawl 795 and a laterally extending bifurcated arm 799 integrally formed with the pawl. Rotation of the bifurcated arm 799 rotates a trigger operating shaft 801 clockwise by means of a trigger shaft operating arm 802 which is engaged by the bifurcated end of arm 799. The trigger operating shaft 801 is supported by a suitable bearing 803 in a wall of bearing support 636 and another bearing 804 forwardly mounted on the horizontal flat tened base portion of the bearing support 636. The trigger .shaft 801 is splined and carries a group of elements the majority number of which are spline-secured thereto, as will more fully appear as the description proceeds with particular reference being made to FIG. 13. Looking forward along trigger shaft 801, actuating arm 802 is splined to the extreme rearward end of the shaft. The next element on the trigger shaft is a spring-biased shaft return pawl 805 which is splined to the shaft and is biased downwardly to return shaft 801 to its initial position and to resiliently maintain the finger 797 of round actuated pawl 795 in the path of incoming rounds. Next forward on trigger shaft 801 is a trigger finger operator 806 splined to the shaft, a sear trigger finger 807 independently operable on the shaft axis and not splined thereto and a trigger finger limit stop 808 splined to the extreme forward end of the shaft.

In greater detail, the shaft return pawl 805 has a lateral extension 809 which is urged downwardly by a spring actuated plunger assembly 811 mounted on the forward face of the bearing support 636. Upwardly extending lug 810 functions to limit rotation of shaft 801 by striking an abutment 810 provided on hearing support 636 (FIG. 9). By this arrangement, the actuating arm 802 is caused to move counterclockwise and urge the round actuated pawl 795 clockwise into round engaging position, as shown in FIG. 10.

The trigger finger operator 806 has an L-shaped, lateral extension 812, a vertical portion 813 of which supports the end of a spring urged forked shaft 814, the forked end 815 thereof being pinned to an upwardly and rearwardly extending crank arm 816 of the sear trigger finger 807. The crank arm 816 is offset rearwardly as at 817 to overlie the shaft portion of the trigger finger operator 812 thereby aligning forked shaft 814 with the aperture 818 in trigger finger operator 806 when forked end 815 is pin connected to arm 816 as at 819 in FIG. 11. The trigger finger 807 is centrally bored as at 821 (FIG. 13) to a larger diameter than that of shaft 801 and is journaled for independent rotation on boss 822 formed on the rear face of the trigger finger limit stop 808. The stop 808 has a lateral extension 823 which engages a lug 824 laterally offset and forwardly extending from trigger finger 807 thus limiting the clockwise free rotation of the trigger. I

Thus, as the trigger shaft 801 is rotated in a clockwise direction by the round actuated pawl 795, the trigger finger operator 806 also rotates clockwise urging in a clockwise direction crank arm 816, through the medium of the spring urged "forked shaft siaand causes finger 807 to bear on the sear cam 781 with suificient force to release the sear locking pawl 773.

As the slide 644 moves forward after buffering by slide buffer 754 and is scared or latched as shown in FIG. 12, the counterclockwise movement of the sear cam 781 is translated into a severe upward shock on trigger finger 807. This shock is dissipated by the trigger finger moving counterclockwise on boss 822, independent of the relatively stationary trigger shaft, and against the spring action on the forked shaft 814.

Referring to FIG. 12, the slide 644 is released in response to an incoming round which engages round actuated pawl 795. As afore-mentioned, this engagement causes the various elements of the sear trigger mechanism 794 to function to rotate trigger finger 807 in a downward direction and into driving engagement with trigger finger engaging arm 784. Therefore, clockwise rotation of scar cam 781 is effected to enable sear locking pawl 773 to be cammed out of searing or latching engagement with the inclined forward surfaces of stop projections 793 on slide 644 by action of the carnrning angle of the mating surfaces on the stop projections and the sear locking pawl. The slide therefore is released and driven forward in the manner previously described.

Summary of Operation Gun Mechanism The operation of the gun mechanism 107 will be summarized briefly at this point and in greater detail hereinbelow. After the transfer mechanism 112 has delivered a round to the entry side of the gun mechanism, the round is urged beyond the round engaging pawls 593 by forward pressure exerted by the next succeeding round if the round is properly positioned and the preceding round has fired. The round engaging pawls 593, mounted on the top cover 612 of the gun mechanism, restrainthe round or permit the round to enter the gun mechanism depending on whether or not the proper firing conditions have been met.

The gun is charged by the action of a piston, not shown 1n this application but fully disclosed in the aforementioned copending application. This piston is drivenby any suitable pressure fluid to move the operating slide rearwardly into its seared or latched position prior to initial firing of the gun. When the slide is in its seared or latched position, it is in a condition for moving a round to the firing position. When the 'slide is released it will be driven forwardly to rotate feed sprocket 611 and rnove a round to the firing position and subsequent feed ing and firing of ammunition will initiate automatic operation. After the round enters the gun mechanism, and has been moved upwardly and laterally along rails 827 and 637 into alignment with the gun barrel 109 by feed sprocket 611, the gas sealing collar 656 moves into sealing engagement with the open forward end of the round container to thereby seal the round to the barrel. The round is fired from the container into and through the barrel, the firing charges igniting the propellant which,

in turn, accelerates the projectile to high velocity. The gun slide 644 is moved rearwardly by means of a buffer and expansion cylinder, not shown, which receives recoil pressure gases through ports, not shown, which communicate the latter with the interior of the gun barrel. Suitable slide return springs, not shown, are compressed by the slide as it travels rearwardly under the action of the recoil pressure gases. The slide is latched or seared slightly forward of its rearmost position by sear mechanism 76 5 if proper firing conditions do not exist at this time. The sear mechanism 764 is released by subsequent incoming rounds which are admitted only if proper firing conditions exist, that is, if the next succeeding incoming round is in the correct feeding position and the previous round has properly fired. This next round depresses the round actuated pawl 795 which permits the slide to be driven forward by the slide return springs. The feed sprocket 611 is rotated by cam surface 649 on the slide as the latter moves forward to thereby move the next round into firing position. Thus, automatic feed and fire will continue so long as the firing switch in any suitable firing circuit, such, for example, as that disclosed in application Serial No. 663,319, aforementioned, remains closed and the rounds continue to fire and feed properly. Feed sprocket 611 also functions to move the empty round case of each round immediately after the round is fired out of the gun mechanism 197 and into the case ejection system 111.

Thus, it will be seen that in the normal cycle of firing, the operating slide is gas driven rearwardly, is buffered at its rearmost point of travel and .is then moved forwardly by spring compression to a forwardmost position where it is buffered and the cycle is then repeated.

However, upon the occurrence of an unusual condition, the normal firing cycle will be interrupted, the operating slide remaining in a latched or seared position slightly forward of its rearward limit of travel. For example, to charge the gun and initiate automatic firing after loaded rounds have been moved to the round exit of the transfer mechanism, the operating slide is moved rearwardly by pressurized fiuid from any suitable reservoir. The operating slide is latched by the sear mechanism, and only when rounds have been advanced by the transfer mechanism into a triggering position in the gun will the sear be released to allow the slide to move forwardly and laterally displace a round into the firing position. Another condition under which the slide is seared is when the rounds are by-passed prior to reaching the trigger position. For example, when a hangfire occurs, the delay in firing will cause an accumulation of rounds in the vicinity of the ammunition by-pass mechanism (not shown) and efifect operation of the bypass mechanism. When the hangfire round finally fires, the slide will be driven rearwardly and latched in its seared position and will remain seared until a round entering the gun mechanism releases the sear mechanism. In the event of a misfire, the cycle will be the same as in charging the gun when it is vdesired to initially effect firing operations.

The slide is latched in its seared position by coaction between structure on the slide and the searing mechanism. During the searing or latching operation, as the slide moves rearwardly, the forward face of the striker arm 736 is struck by an abrupt inclined surface 788 on an upwardly projecting cam portion 789 formed in the rear floor portion of the slide. This impact of surface 788 against arm 7% rotates cam 731 in a clockwise direction against the compression of spring plunger 787. Thus, the striker arm 736 is retracted until the slide is moved far enough rearwardly so that the striker arm may drop into groove 791. The slide is buffered and then upon forward motion of the slide the rear face of the striker arm 786 contacts the rearwardly inclined wall 792 of groove 791 thereby rotating cam 781 counterclockwise. The entire lock pawl 773 is caused to be rotated counterclockwise and the slide engaging latch 778 engages the stop projections 793 formed at the rear portion of the slide to thereby latch or sear the slide in a position slightly forward of its rearwardmost limit of travel.

As afore-mentioned, the slide is released from the seared position by a round moving from the transfer mechanism into the gun mechanism. During the motion of the round into the gun mechanism, the round contacts and moves the first element of the sear triggering or slide unlatching mechanism 7%. Lateral and upward motion of the round along rails 63% and 639, as the latter moves into the gun mechanism, bring the round into engagement with the round actuated pawl 795 causing the latter to move in a counterclockwise direction as viewed in FIG. 10. As best illustrated in FIGS. 9 through 13, such rotation of pawl 795 rotates the trigger operating shaft 8% to also rotate the trigger finger operator 8136 in a clockwise direction, crank arm 816 in a clockwise direction, and causes finger 807 to bear on the sear earn 781 with sufiicient force to release the slide engaging latch or sear locking pawl 773 by raising the latch portion 778 thereof out of searing and latching engagement with the stop projections 793 on the slide 644 whereupon the slide is driven forward in the manner previously described.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within -he scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In an automatic weapon having a barrel, a receiver defining a transverse round passage, drive means for moving rounds into a. firing position and carried in the receiver, a gas operated reciprocable slide connected to said drive means for effecting movement of the latter upon the firing of each round, and a scar and trigger mechanism for the slide comprising; sear means engageabie with the slide for restraining the latter against movement, release means for moving said sear means to a disengaged position relative to said slide upon round passage into the receiver, and a firing pin mechanism for firing successive rounds in the receiver after each round is placed in a predetermined position by the drive means, said sear means comprising a housing and means for aligning the latter during sear engagement and disengagement with said slide, latch means pivotally mounted within said housing for latching engagement with said slide when the latter has been driven to a predetermined position by the firing or" a round, and means for actuating said latch means to a position of disengagement with said slide when the succeeding round enters the receiver, said latch means comprising a plurality of series of pro jections on said slide and a latch rotatably mounted in said housing and engageable with at least one of the series of said projections, said actuating means comprising means on said latch forward of the pivot point of the latter and defining a verticahy aligned slot, a cam member rotatably mounted in said slot and having a series of arms formed thereon, one of said arms being a latch engaging arm in engagement with a forward face of said latch at a point vertically spaced from the latch pivot point, another of said arms being vertically depending and engageable with another of said projectrons during forward and rearward movement of the slide.

2. In an automatic weapon having a barrel, a receiver defining a transverse round passage, drive means for moving rounds into a firing position and carried in the receiver, a gas operated reciprocable slide connected to said drive means for eltecting movement of the latter upon the firing of each round, and a scar and trigger mechanism for the slide comprising; sear means engageable with the slide for restraining the latter against movement, release means for moving said sear means to a disengaged position relative to said slide upon round passage into the reeeiver, and a firing pin mechanism for firing successive rounds in the receiver after each round is placed in a predetermined position by the drive means, said release means comprising a trigger member actuated by rounds passing through said receiver prior to reaching the firing position, linkage means connecting said trigger member to said sear means for effecting movement of said sear means from a latched position to an unlatehed position when said trigger member is actuated, said linkage means in eluding a release arm engageable with said sear means, a rotatable shaft for supporting said release arm, and resilient means for biasing said release arm to a sear engaging position and for biasing said trigger member into the path of round travel Within said receiver and prior to the arrival of said rounds at the firing position.

3. In an automatic weapon having a barrel, a receiver defining a transverse round passage, drive means for moving into a firing position and carried in the receiver, a gas operated reeiprocable slide connected to said drive means for effecting movement of the latter upon the firing of each round, and a scar and trigger mechanism for the slide comprising; sear means engageablewith the slide for restraining the latter against movement, release means for moving said sear means to a disengaged position relative to said slide upon round passage into the receiver, and a firing pin mechanism for firing successive rounds in the receiver after each round is placed in a predetermined position by the drive means, said sear means comprises a housing and means for aligning the latter during a position of disengagement with said slide when the succeeding round enters the receiver, said latch means comprises a plurality of series of projections on said slide and a latch rotatably mounted in said housing and engageable with at least one of the series of said projections, said release means comprises an actuating trigger finger engageable with said rotatable latch, means for supporting said trigger finger, said last mentioned means including a rotatable shaft, means for connecting said shaft to said trigger finger for effecting positive movement of the trigger finger in one direction, resilient means for connecting said trigger finger to said shaft for causing yieldable movement of the trigger finger in the opposite direction, a round actuated pawl located for contact by rounds passing through the receiver prior to their arrival at the firing position, and means for connecting said pawl sear engagement and disengagement with said slide, latch means pivotally mounted within said housing for latching engagement with said slide when the latter has been round, and means for actuating said latch means to to said rotatable shaft whereby motion of the pawl effects actuation of the trigger finger.

4. The scar and trigger mechanism set forth in claim 2 wherein said linkage means further includes means for limiting the motion of said release arm between prede ter mined limits, means connecting said trigger member to said rotatable shaft and including an arm secured to the shaft, said arm being disposed for engagement by one end of said trigger member for effecting movement of said rotatable shaft in accordance with trigger movement.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,158 ,063 November 24 1964 David F. Anderson et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 11, line 32, after "been" insert driven to a predetermined position by the firing of a Signed and sealed this 10th day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER' EDWARD J. BRENNER Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,158,063 November 24, 1964 David P. Anderson et all It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 11, line 32, after "been" insert driven to a predetermined position by the firing of a Signed and sealed this 10th day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN AN AUTOMATIC WEAPON HAVING A BARREL, A RECEIVER DEFINING A TRANSVERSE ROUND PASSAGE, DRIVE MEANS FOR MOVING ROUNDS INTO A FIRING POSITION AND CARRIED IN THE RECEIVER, A GAS OPERATED RECIPROCABLE SLIDE CONNECTED TO SAID DRIVE MEANS FOR EFFECTING MOVEMENT OF THE LATTER UPON THE FIRING OF EACH ROUND, AND A SEAR AND TRIGGER MECHANISM FOR THE SLIDE COMPRISING; SEAR MEANS ENGAGEABLE WITH THE SLIDE FOR RESTRAINING THE LATTER AGAINST MOVEMENT, RELEASE MEANS FOR MOVING SAID SEAR MEANS TO A DISENGAGED POSITION RELATIVE TO SAID SLIDE UPON ROUND PASSAGE INTO THE RECEIVER, AND A FIRING PIN MECHANISM FOR FIRING SUCCESSIVE ROUNDS IN THE RECEIVER AFTER EACH ROUND IS PLACED IN A PREDETERMINED POSITION BY THE DRIVE MEANS, SAID SEAR MEANS COMPRISING A HOUSING AND MEANS FOR ALIGNING THE LATTER DURING SEAR ENGAGEMENT AND DISENGAGEMENT WITH SAID SLIDE, LATCH MEANS PIVOTALLY MOUNTED WITHIN SAID HOUSING FOR LATCHING ENGAGEMENT WITH SAID SLIDE WHEN THE LATTER HAS BEEN DRIVEN TO A PREDETERMINED POSITION BY THE FIRING OF A ROUND, AND MEANS FOR ACTUATING SAID LATCH MEANS TO A POSITION OF DISENGAGEMENT WITH SAID SLIDE WHEN THE SUCCEEDING ROUND ENTERS THE RECEIVER, SAID LATCH MEANS COMPRISING A PLURALITY OF SERIES OF PROJECTIONS ON SAID SLIDE AND A LATCH ROTATABLY MOUNTED IN SAID HOUSING AND ENGAGEABLE WITH AT LEAST ONE OF THE SERIES OF SAID PROJECTIONS, SAID ACTUATING MEANS COMPRISING MEANS ON SAID LATCH FORWARD OF THE PIVOT POINT OF THE LATTER AND DEFINING A VERTICALLY ALIGNED SLOT, A CAM MEMBER ROTATABLY MOUNTED IN SAID SLOT AND HAVING A SERIES OF ARMS FORMED THEREON, ONE OF SAID ARMS BEING A LATCH ENGAGING ARM IN ENGAGEMENT WITH A FORWARD FACE OF SAID LATCH AT A POINT VERTICALLY SPACED FROM THE LATCH PIVOT POINT, ANOTHER OF SAID ARMS BEING VERTICALLY DEPENDING AND ENGAGEABLE WITH ANOTHER OF SAID PROJECTIONS DURING FORWARD AND REARWARD MOVEMENT OF THE SLIDE. 